PURPOSE: To obtain a light-weight structure exhibiting high impact resistance and rigidity by extruding a molten film or sheet of a polymeric material, superposing a glass cloth layer on surfaces of polymer layers, and compressively nipping the superposed layers.

CONSTITUTION: Molten polymer of polymeric material is supplied by an extruder 22 through a die 23 to form a partly molten polymer layer 12. The layer 12 is supplied to a compression nip 24 formed of a pair of compression rolls 26, 28. Glass cloth layers 14, 16 supplied as continuous webs from corresponding supply rolls 30, 32 are conveyed to the nip 24 in a relation opposed to the layer 12. Since the material is molten, the material flows into the layers 14, 16 to form a core structure 10. The obtained structure 10 is conveyed around an idler roll or a guide roll 34 to a machining process station of a downstream side.